Fastening tools, such as, for example, manually operated staple guns, allow an operator of the device to use a single hand in order to operate a handle or the like. Movement of the handle causes the compression of a spring in the tool. When the energy in the spring is released, a fastener is expelled from the fastening device. The operation of the handle to compress the spring and the subsequent release of the energy built up in the spring typically results from one motion of the handle. One type of fastening tool is a forward acting stapler, which is commonly known in the art, and has a handle which is pivoted at one end, the rear end, of the fastening device body. Another type of fastening tool is a rearward acting stapler, also commonly known in the art.
One example of a commonly known rearward acting stapler is disclosed in U.S. Pat. No. 2,671,215 issued to Abrams, which discloses a staple gun manufactured by Arrow. A handle is pivoted at or near the front of the staple gun. Pressing down on the handle behind the pivot at the free end of the handle compresses a coil spring within the tool. The motion of the handle rotates a pivotally attached lever arm, which in turn raises a plunger assembly including a plunger. At a pre-determined point of travel of the handle, the lever arm arcs sufficiently such that it releases the plunger assembly. The plunger is driven downwards by the force provided by the decompression of the coil spring.
With the advent of forward acting staplers, such as one disclosed is U.S. Pat. No. 5,699,949 issued to Marks, the handle is attached and pivoted at the rear of the stapler. In this configuration, it may be easier for the user to apply a load to the handle, because the load applied to the handle is more in line with the plunger. This may result in a more efficient transfer of energy through to the staple, and therefore, an improved fastening mechanism. However, the input load required to depress the handle is identical to, or substantially the same as, rearward acting staplers and is therefore still substantial.
There are certain drawbacks to conventional forward and rearward acting staplers. For example, the act of depressing the handle (and thus “loading” the device) and the act of ejection of a fastener occur as one event that happens virtually simultaneously. Oftentimes it may be difficult to apply sufficient force to the handle if one is outstretched or in some other awkward stance, or if one is trying to fasten onto a backing that is not rigidly supported. Thus, it may be desirable to have a fastening device wherein the handle can be depressed (thus putting the device in a “loaded” state) in one event, and ejection of the fastener can be occur as a separate event.
Electronic staple devices do not require manual generation of energy stored in a compression spring. Electronic staple devices, however, suffer the disadvantage of, among other things, requiring a power source and the commensurate weight penalty which comes with the ancillary mechanisms required for proper and safe operation.
Forward acting manual staple guns are well known in the art. These conventional staple guns, however, do not allow a user to store the energy within the staple gun in one step and then release the stored energy in an independent step. The provision of a mechanism for independently releasing the stored energy may be advantageous to a user of a staple gun in many instances. For example, if the user of a staple gun is required to apply a fastening device or staple above the user's head or just out of the user's reach, the user would not be able to use traditional manual staple guns to apply the fastening device with much success. This is because conventional staple guns eject the staple virtually simultaneously with the application of a considerable force applied by the user to the operating handle, i.e., squeezing the handle.
It would be therefore advantageous to develop an improved fastening device that overcomes the disadvantages described above. In particular, it may be advantageous to provide an improved fastening device wherein depressing the handle of a device to generate energy within the fastening device is one event, and the actual ejection of the fastener (e.g., staples, nails or other types of fasteners) from the fastening device is a separate, distinct event.